IIR_Filter = iir();

fs = 8000;
N=64;
n=0:N-1;
y=sin(2*pi*500/fs*n)+sin(2*pi*1000/fs*n)+sin(2*pi*3000/fs*n);
y_f = filter(IIR_Filter,y);

subplot 211;
plot(y);
subplot 212;
plot(y_f);